First, a bit of background on the need for a "Special Flight Permit" (also known as a "Ferry Permit").
14 CFR Part 21.197 - Special flight permits, requires a special flight permit ("ferry permit") in order to fly an aircraft that "may not currently meet applicable airworthiness requirements but is capable of safe flight...." for the purpose of, among other reasons, "Flying the aircraft to a base where repairs, alterations, or maintenance are to be performed..."
Since the helicopter in question is not "airworthy" I think that FAR 91.7 (a)
No person may operate a civil aircraft unless it is in an airworthy condition.
would apply and you could not operate it without a ferry permit (whether or not you're flying it at 5 feet in the air or 500 feet in the air). When you're in the air (helicopter, airplane, balloon, etc.) you are "flying."
Just because the phrase "hover-taxi" is used does not mean it's not flying. The pilot would also have to be appropriately rated/current in helicopters.